Improvement in combined high and low-pressure engines



THOMAS L. JONES, OF NATCHEZ, MISSISSIPPI.

Letters Patent No. 94,891,datedrSeptember I4, 1869. I IM' i IMPROVENIENTIN' CCMBINED HIGH AAND LOW-PRESSURE ENGINES.

The Schedule referred to in th'ese Letters Patent and making part 0f theSame- To all whom it may' concern:

Be it known that I, THOMAS L. J oNns, of Natchez, in the county ofAdams, and State of Mississippi, `have invented a'new and-.improvedCombined High and Low-Pressure "Engiriej and I do hereby declare thatthe following is a fhll, clear, and exactdescription of the constructionand operation of the same, reference beiughad: to the accompanyingdrawings, `making a part of this specification, in whichp Figures l and2 are side-views, showing the valves in dii'erent positions, a portionl,of the walls of the valve-chests being broken away, to reveal theoperation of the parts enclosed therein.

i Figure 3 isia detached View of valve n n.

This invention is an adaptation of my combined high and vlow-pressuresteam-engine, patented April 14, 1868, No. 76,776, ,and` consists. in anew arrangement ofparts, whereby]1A am enabled to use my atmosphericvalv'e (a portion of `my patent) in connection with that i'orm of`engines now in use on our western rivers, enabling them, with s'lightaddition of machinery and cost, to retain their present high-pressuresteamboat-eugines,` and, with my improvement, giving them the advantageof a vacuum, increasing the speed of theirl forty-foot paddle-wheelsthree or four revolutions per minute, without additional press- Vure ofsteam.

This improvement I have practically tested, on a large scale, atLouisville, .Kentucky, on onel of our river steamboats, and it hasproved to work to perfectionI in all its particulars. l

In thedrawings-- A is the cylinder-head; i

' B, the piston-rod;

`(l, the cross-head;

E F, two reciprocating rods, which wol-.k the valves,

themselves operated, `by a cam and yoke, from the main shaft;

a side pipe, arranged alongside of the cylinder, oil-.the opposite sideto that Voccupied by the steam-chest, the latter not being shownin thedraw- .iussi v I and J, two rock-shafts, the former worked by thev rodE, and thelatter by the rod I" t t', a A,rocking or lifting-lever,atiixed to shaft I. L L', two levers, operated, alternately, bythe toesH H, pipes', leading. from the ends of the main cylf inder into the sidepipe G, at each end of 'the latter,

and shown here indotted lines; v K K', rods, connecting the levers L Lto valves that open and close pipesV H H,respectively, andthusalternately opening a .passage'for the steam in its centre, throughwhich steam exhz'iusts from thev valve-chest to the open air;

N', a side pipe, attached to the side of va'ilve-chest N; and

R, a pipe, leading from the centre of side pipe N to the condenser.

VThe operation of these severalparts `is briefly as v follows:

Then the vsteam exhausts from theleft-hand end of the main cylinder, itpasses, through pipe H, into side vpipe G, the toe i being lifted, so asto open pipe H, and the toe t" being depressed, s'o as to close pipe Hat that moment, as shown in tig. 1

When the steam exhausts from the right-hand endof the main cylinder, italso passes into side pipe G,

but through pipe H', lever L being up,and lever L down, as shown in tig.2.

From side pipe G, in either case, the steam, under considerablepressure, passes directly into valve-chest M, where it forces up anatmospheric valve, m ml, and blowsofi, through pipe Q, down to anequilibrium with the atmosphere, or fifteen vpounds to the square inch.f

Ihe valve m m then falls vby its own weight, (assisted, if necessary, bythe action ofa spring, m2,)

and, at lthat instant, two balanced.. valves, connected on one sten1,iz1i1,in chest N, open and establish a direct communication from sidepipeG to the condenser, through the parts O M l N N It', and instantly, bythe action of Vthe condenser, the remaining fifteen pounds of' steam arecondensed, and a vacuuxn produced in the exhaust-end ofthe maincylinder. l

The li-ve steam is being admitted to the opposite end of the maincylinder meanwhile, so that the piston that operates rod B has a vacuumf 'o'n one side, and a full head of steam on the other side, at the sameinstant, and thus acts with the combined force `ot' a high-pressure anda-low-pressure engine.

The valves an m1 and a n1 are operated by means of a lifting-foot onvshaft J, similarto that show-n at i fi.

The two' valve-Steins m1 al are connected to a cross# gine awhile,

'steam to exhaust to the open air, whatever maybe the position of thecross-head and the other valves.

This arrangement not only insures the raising and lowering of va-lve mm1at the proper instant, but pre- `vents all danger should anythingconnected with steam-chest N, its valves, or the condenser, get out oforder, or refuse to act, since, in such case, the steam would simplyblow off wit-hout going to the condenser, just as in a simplehigh-pressure engine. Indeed, it can be made to act as a-high-pressurecngine alone, by raising the cross-head, and fastening it up, in whichposition the `two balanced condenservalves 'n nl will be securelyseated, and the valve m fm.l open.

In my large engines, I prom'de a sleeve aud lever v over rock-shaft J,for the special purpose of thus raising the cross-head, .and fasteningit.

Among other advantages of this arrangement, it enables the engineer toascertain, at any time, just what gain results 4from the employment ofthe condenser-exhaust in addition. to the open-air exhaust. He has onlyto shut ofi` the former, and run the ennoting the number of revolutionsper and run the, engine an equal when acomparison of the show whichminute, and then open it, time, noting the revolutions, revolutions madeunder each condition will is most advantageous.

In the large river-boats on which this improvement.

has been most fully and satisfactorily tested and demonstrated, a gainof three to four revolutions per minute over the high-.pressure enginehas been. noted whenever the combination was employed.

In order to assist in securely shutting the valves n al, a spring, u2,may be provided under the valvechest.

The valve-rod nl will require but little packing, since the chest N isso connected with the condenser that the outward pressure is nearlyalways neutralized. Indeed, the pressure is generally inward onthis'chest, so that the steam has no tendency whatever to escape fromit, except to the condenser.

The throw of the valves m m1 n a1 maybe adjusted by changing theirposition on their stems, or by adjusting the cross-head or. the.liftiug-foot, or moving the cam employed at the main shaft to work therod F. It is, therefore,- perfectly ,easy to regulate the working of anypart of the apparatus, and it will be especially observed that theengine with my improvement works as well backward as forward.v

In fig. 1, the piston is at the right-hand end of the main cylinder, andthe exhaust H is opening. Just at this instant, the cross-head raisesvalve m m1, making a free passage from the exhaust-end of the cylinderto the open air, and allowing all but fifteen pounds of steam to blowott'. At the same instant, the valve a al has seated, cutting off thecommunication with the condenser. As it takes but an instant to blowoli` all the steam above fifteen pounds, the cross-head now comes downquickly, allowing valve m 1nl to close, and opening valve a al, so thatthe remaining fifteen pounds may go to the condenser. The passage tothecondenser continues open during the remainder of the stroke, andis onlyclosed when, on the return-stroke, the toe i opens the exhaust H', attheopposite end of the cylinder. At that instant, it closes momentarily, toallow the newly-exhausted steam to blow off to fifteen pounds, when itagain unseats, as shown in `tig. 2, and keeps the way to the condenseropen to the end of the return-stroke, and so on, as long as the engineis in operation. i

The valves n nl are balanced, consisting of a frame, e, two annularrings, a a, attached to the frame, and working steam-tight in the chest,two lcircular plates, n n, opening and closing the central orifice ofthe an nular plates, tached to that part of rod al which is fastened tothe cross-head, and the plates a n being attached to that part of saidrod which extends down through the bot tom of the valve-chest, and isconnected to the spring.- It will be seen that the rod nl is thus in twoparts, connected only by the slidingy parts e a n, as described. Theconstruction of this valve is clearly exhibited in fic. 3.

Itowill be observed that the open-air exhaust Q communicates with theside of the valve-chest M, so that the valve m can rise above it-anarrangement which allows the steam to blow off before the valve reachesthe end of its upward throw.

The upper end of the valve-chest, above the orificev Q, thus forms anair-chamber, which cushions the valve, and prevents all jar and shock. y

In practice, the valve is found to work as smoothly and silently underfull head of steam as if operated by hand.

If necessary', the valve might be made to rise into the mouth of adownward-projecting tube, closed steam and air-tight at its upper end,in which case a perfect air-cushion would be provided for the Valve.

I do not wish to confine myself to the particular form of valve shown infig. 3, but may use any other construction Iwhich,'adopted in place ofthat, would answer the purpose as well.

,When I employ the form of valve described, Ias shown, the simplicityand beauty of the operation of the parts are particularly noticeable,the simplevertical movement of the crosshead performing three functions,viz, operating the valve m m1, raising and lowering the frame e andannular plates ara, and moving, at the proper moment, the valve-platesn. It would be diiricult to effect such complex movements with simplermechanism.

Having thus described my invention,

What I claim as new, and desire to secure by Letters Patent, is-- e 1.The combination of pipe 0,valvecl1est M, valve a, and pipe Q, of thevalve-chest, with an air-chamber above it, substantially as set forth. V

2. The cross-head T, in combination with the valvestem a, fixed to it bya set-screw, the valve-stem mi sliding loosely through it, and the stop"u, to regulate the distance which the rod m1 slides through thecrossfhead, substantially as and for the purposes set forth.

3." lhe combination and arrangement of the valvechests M N, valves on m1n al, passage P, pipes Q R, cross-head T, and springs fm? al,substantially as described.

the frame and annular plates being atwhen the latter is arranged at theside-

